That can be all it takes to lose player's interest in her side, because the protagonist is no longer the centre in that case. Example being, people were fine with Ronnie and Sid teasing through the computer because that still had the protagonist as the centre. But if you were to say that Ronnie has been hooking up, to whatever degree, with others while you are a city away, it'll be viewed as cheating. This is in spite of the fact that if you're pursuing the sisters, you are also engaging in cheating.
Perspective is the key. We as protagonist are making that choice that guides the story forward, so we give it a pass because we're self-serving. If you tell us another character is doing something and we have no say, it's viewed as being robbed of that choice and control.
Nobody is going to be complaining that there's more girls for you to get with, but they will complain about how it is they become a part of it. That's ultimately what I'm trying to get at. It'll all come down to how it's written and how it's shown to us.
Like it was said, not every game is for everybody.
We're too far into things to make such a dramatic shift in the storyline.
It may just be that the game is not for you.
As a Loud House Fanfic writer before I wrote the eroge I was always against the entire universe revolving around Lincoln. Yes he's the main character, yes he gets most of the girls, but there are other characters with agency.
Lincoln will never steal his mother from his Father, Lincoln won't steal Vanessa from Clyde. Luna loves Sam. Lori loves Bobby.
If Ronnie Anne showing some agency in proactively getting another girl to be in Lincoln's Harem because it's also a friend of hers she's know for awhile turns some people off.
Well I guess they're just turned off.
Like I honestly don't know what there is to say beyond that. If people don't want to play the game because of that, it makes me sad, but we're not going to make everyone happy.
There are folks who want Lori to be a virgin who never loved Bobby, but in our world Lori loves Bobby and lost her virginity to him.
If every girl in the game just fell before the might of Lincoln's log with no complications, twists, turns and surprises it would be a much shorter game and probably a more boring one at that.
At least I think so.